Electronics Forum | Tue Aug 02 10:46:03 EDT 2016 | proceng1
We are getting more and more customers wanting LED boards built on White Solder Mask. Well our printers do not get as much contrast between the white mask and the plated fiducial pad, and often the camera only sees white. Other than playing with
Electronics Forum | Fri Jul 24 07:43:56 EDT 2009 | davef
Your customer is correct. You are doing something wrong in your hand soldering process. Solder balls are a process indicator. Areas to assess are: * Moisture content of the bare board * Thickness of the copper plating in the through holes * Temperatu
Electronics Forum | Wed Sep 18 19:43:12 EDT 2002 | dragonslayr
One more variable I've remembered - pad height with respect to solder mask height. Pads being too low can cause stencil "gasketing" problems that in turn allow more paste to be deposited than needed. Are your fabs HASL or some other media?
Electronics Forum | Mon Aug 14 05:45:16 EDT 2023 | dimamalin
First, this is the result of bad printer setup. Adjust knife pressure, PCB gap, separation speed, tooling, and stencil cleaning. Pay attention to the coating of contacts pad and height of solder mask of PCB.
Electronics Forum | Mon Aug 14 13:08:00 EDT 2023 | dimamalin
Similar issues arose for me in cases where the contact pads of components were located below the solder mask level. Ordering a thinner stencil might potentially solve the problem.
Electronics Forum | Wed Sep 18 12:35:56 EDT 2002 | stepheno
Fourth - > back to design of PCB. Are there solder dams of > mask between the pads? If yes, that helps. If > not, pay close attention to stencil aperture > width and be sure that the aperture deposits less > paste by 1-2 mils per pad, centered o
Electronics Forum | Mon Apr 19 20:49:13 EDT 1999 | Dave F
| Netters, | | When I reflow a PCB there is a discoloration of silkscreen and mask. It appears if Profile is too hot! But I dont think so, maybe I'm wrong? | | 1. Kester 293 no clean | 2. 2.1 C/s for 30s to 150 C | 3. .5 - .7 C/s for 60s to 185
Electronics Forum | Fri Jul 13 11:33:54 EDT 2007 | realchunks
Just starting and already responsible for product quality and machine adjustment? Wow, you poor bastard. Ok, I will assume this problem happens on the bottom side of the board with a thru-hole IC. The short occurs on the side that doesn't have the
Electronics Forum | Mon Apr 17 19:30:27 EDT 2000 | Boca
All of the above is good stuff. To add, I have seen this several times if the assembly is wavesoldered. Heat from the wave can partially reflow the top side SM solder joints and weaken them. To test, check joint strength before wave and then after
Electronics Forum | Sat Feb 05 09:08:18 EST 2000 | Dave F
Casimir: Let me expand on something that I said in my response to your thread on ionic testing. Generally, no-clean people don�t use ROSE testing as part of their process control, because the ROSE test is essentially washing your board in DI/IPA �
.gif)
